Motor control



Sept. 4, 1928. 1,683,221

' L. J. WEBER MOTOR CONTROL Filed July 15, 1926 Inventor I Lbuis J.Weber,

His Attorney? Patented Sept. 4, 1928.

LOUIS 'J'.

UNITED STATES o PATENT oF-Fic-E.

VIEBER, or scnnnEorAnY, New YORK, ASSIGNOR 'ro GENERAL nnnern o comrnrw,A CORPORATION or new YORK.

MOTOR CONTROL.-

, The invention relates to the control of electric motors, particularlyreversible inotors arranged for limited operationin at least one if notboth directions of rotation. In the latter case, as where the motorconnected. to drive directly a reversible device having fixed limits ofoperation, such for example as a reciprocatingpump, planing maehine, orthe like, it is a common practice to reverse the device by reversing thedriving motor through. the agency of suitable limit switch mechanismupon reaching suitable limits of operation in each ,directionotoperation. 2 V

The object of the present invention is to provide an improved form ofcontrol for automatically effecting the reversal of the motor when adesired limit of operation of the motor in either one or bothcll.r;ctions or the operation is reached. Briefly, this is accomplishedin'accordancewith a. preferred form of my present invention by arrangingthe motor so that it is mechanically retarded preferably until it stallswhen the desired limit of operation in either one or both directions isreached. This causes the motor power current to increase and Ipro'videelectic-responsive means operable responsively tot-he increasedor stalled current of the motor for effecting a reversal thereof.

' Vflhile my present invention has a wide tield or" application in (111ordinary types of reversible motor control systems'it is particularlyadvantageous for controlling a reversibleelectric motor under conditionswhere it is either desirable or imperative that all of thec'ontrolapparatus be located remotely from the motor as well as from the devicedriven thereby. Under such conditions'the use of the ordinary type oflimit switch re versin; control obviously is (impossible. Thus where amotor is reversed to drive a reciprocating pump in each direction andthe motor as well as the pump is to beoperated at the bottom of a deepwell casing of relatively small diameter, as in an oil well or the like,it eztrcmcly desirable, it not absolutely necessary. lor satisfactoryoperation, that the motor reversing control equipment be located abovethe top of the well. In such service my present invention enables all ofthe motor control equipment to be placed in a convenient and accessiblelocation at the top of the well with only the electric power conductorsor cable extending 192e- Serial no. 122,726.

down theorising totheimotor at the bottom $01? the well. As previouslyindicated, my

improved motor reversing control equipment includes a suitableelectroresponsive device which is operated responsively to the increasedcurrent of the motor flowing in the power conductors on cable when'themotor is stalled and serves 'torperiodically reverse the motor as itstallsat each-limit of'operation of thereciprocating pump. I

In the accompanying drawing, the single figure diagrammaticallyillustrates the invention embodied in an automatic control system forreversing a three-phase alternating current motor connected to drive areciproeating pump suitable for deep oil well servicealthough it will beunderstood that the invention may be applied with equal advantage tocontrol other types of electric motors in similar service f' Referringto the drawing, the reversible motorlQwhieh is to be controlled inaccordance with my present invention is shown as of the: threephasealternating current type and is connected to drive the plunger 11 of thereciprocating pump 12 through the agency of suitable screw gearmechanism as illustrated in the draw ng. l -fhile the design andstructure of thereciprocating pump together with the-,mechanicalconnection of the motor thereof form no part of my present invention, itmay be noted'tha-t the pum shown'is adapted to fit into and close thewell casin 'l3. Also, the pump is provided with an inict valve 14 toadmit fluid-into the cyl inder of the pump when the piston is raised, aswell asan outlet valve 15 for-permitting tie fluid toIbe foreed upwardin the well 3 whenthe pump piston is lot erecl. As the automaticreversing of the'motor 10 is dependent in accordance with my inventionupon retarding orstalling the motor at both the-up and down limit ofoperation of the pump piston, the pump preferably is provided withsuit-able butler springs 16 and 17 in order to gradually retardthe motorandthereby insure thatthe motor stalls without jamming or straining thepump drive mocha ism. I

Power is supplied to the motor 10 by' the threeronductor cable 18 fromsuitable three-phase alternating current supply lines it the well knownmanner to control the power,

after may be placed'in a convenient location.-

at the top of the well with only the power cable 18 connected directlyto the motor 10 at the bottom of the well. The elcctrore- 'sponsiveswitches 20 and 21 are arranged in connections of motor 10 so as toreverse the direction of rotation of the motor when one of the switchesis opened and the other switch is closed. As shown'the reversingswitches 20 and 21 are each biased to the circuit opening-position andoperated electromechanically to the closed position, although it will beevident to those skilled in the art thatother forms of reversing switchmechanism may be provided ii desired.

' It will-be seen that the reversingswitches 20 and 21 are providedrespectively with the auxiliary time element control switches 22 and 23which are eacharranged to' close a time interval after the closure ofthe corresponding reversing switch. .lVhile other types of time elementSVltCllGS may be em- 1 1 t1 t i i #1 29 1 a p oycc, 1e .me element swities on anc so as illustrated diagrammatically in the draw ing are ofthe form described and claimed in the Stack Patent No. 1,638,372, issuedAugust 9, 1927, and are provided respectively with the-operatingwindings 24 and 25 which are connected to be energized simultaneouslywith the energization of the operating windings of the correspondingreversing switch.

-The Stack type of'time element device is adapted only for use inalternating current circuits.

gization of the operating windingof the switch 20, the spring connectionwith the [auxiliary time element control switch 22 "put under strain tooperate the contact to the closed position.

At the same time the winding 24: of the time clementfdevi'ceis energizedand attracts the magnetic element associated with the contact. Due tothe fact that the winding 2 1- is energiz'aed with alternating currentthe attraction of the n'lagnetic element is of a pulsating nature. Thusthe magnetic element is periodically atta hed and released, therebyproducing a. time delay in the closure'ot' contact 22.

The energizing circuits of the reversing switches20 and 21 are under thecontrol of the two position electroresponsive relay26. In the formillustrated, the relay 26 is provided with a winding 27 for operatingthe pivoted relay contact 28 into the right hand position in which it isshown and with awinding 29 for operating the contact 28 into its lefthand position.

In accordance with my present invention, the electroresponsive relay 30is provided with an operating winding which is connected to be energizedin accordance with the current of the motor 10 and is arranged Briefly,the arrangement of this timeelement device is such that upon ener-' tooperate the relay to control the reversing of motor 10 responsively to apredetermined increase in the currentsupphed to motor 10 yvhenit ismechanically retarded or stalled.

Since. the starting or inrush current of 'motor 10 also may be ofsutlicient value to effect operation oi relay 30, the time elementswitches 22 and 28 described above are arranged to cooperate with therelay 30 so as to render the latter inelfective during the startingperiod of motor 10. The arrangement is such that the relay 3O cooperateswith the time element'switches 22 and 23 anl the two position relay 26tocontrol the operation of the reversing switches20 and 21 so as toperiodically reverse the power connections of motor 10-when the motorretarded and stalls at each limit of operation of the reciprocating pump12 as Will be described more fully in connection with the operation ofmy improvedcontrol system. V

In accordance with the usual practice the motor 10 may no protectedagainst excessive and prolonged overload current-by a suitthe operatingwinding of the reversing switch 29 extending fromthe upper supply l ne19 through swltch 32, contact 28 of the two poe ltion relay 26, theoperating winding of reversing switch 20 and through the contacts ot theoverload protective device 31 to the middle supply conductor 19.Reversing switch 20 at once closes and may be assumed to establish powerconnections for opera ng motor 10 in the direction of rotationrequiredte raise the piston '11 of the reciprocating pump 12. At thesame time the winding 24- ot thetnne element switch 221s energized inparallel circuit with the operating winding of switch 20 and serves toretard the closure of switch 22 fora time interval after the closure ofswitch 20. This time interval is sufficient to insurethat in case relaymay be operated to the circuit closing position by the starting orinrush current of motor 10 still the relay is ineffective to control theenergization of the twoposition relay 26. However, after the startingand acceleration of motor 10, re-

lay 30 at once returns to the circuit opening position. Thus, after thelapse of the re quired time interval the switch 22 finally closes thecontacts and the motor 10 .QQntinlines 19 sufficient to efiect operationoi the ues'to operate in the direction required to' raise the plunger11.

l/Vhen the pump plunger 11 approaches its upper limit of operation andengages with the butter spring 16,.the motor 10is gradu{ ally stalled,thereby causing the motor toreceive an increased current from thesupply,

relay 30 to close its contacts. '1 his resultsin establishing anenergizing circuit to the operating winding 29 of the relay 26, thecircuit extending from the upper supply line 19 through the controlswitch 32,-the winding 29, the contact oftime element switch 22 whichhas closed as described above, the relay "30 and thence to themiddlesupply line '19. The resulting operation of the relay contact 28 fromits right hand position to its left hand position servesfirsttodeenergize the operating winding of. the re versing switch 20 andthereafter toenergize the operating winding of reversing; switch 21through -a circuit substantially the same as that previously traced inconnect-ion with the energization of switchQO. The opening of switch 20and the closing of switch 21"at once reverses the'torqueof motor 10and'the latter-is set into operation in the direction of rotationrequired to-lower the piston 11.

After the starting or inrush current of motor 10 has decreased to normalvalue the relay 30 returns to the open position as shown in the drawing.Simultaneously with the closure of reversing switch 21 the operatingWinding 25 of the time element switch 23 is energized so as to delay theclosure of'the switch 23 for the time "interval during which the relay30 may be maintained in the'circuit closing position by the starting orinrush current of motor 10. After the switch 23 is finally closed andthe motor 1.0 has operated the pump piston 11 to its lower limit ofoperation themotor 10 again is retarded by engagement with thebufterspring 7 17 until the motor stalls and again the stalled motor currentoperates the relay 30 to the closed position. In this caseclosure ofrelay 3O establishes an energizing circuit for the winding 27 of the twoposition relay 26 extending through .the time element switch Thereuponrelay 26 is returned to the position in which it is shown and functionsto d'eenergize the operating winding. of reversing switch 21 and againenergizes the operating winding of switch 20.

t will be evident that upon the closure of reversing switch 20 the cycleof operation previously described will be repeated indefinitely toreverse the direction of rotation of motor 10 as the plunger llof thereciproeating pump 12 approaches each of its limits of operation,thereby causing the fluid in the well casing 13 to be pumped to the topof V the casing.

From the foregoing it will be evident that equal advantage toothervservice.

' scope of my invention of. reversing motor control that is welladapted-for deep well motor driven pump control although it may beappliedwith Whil I have described and illustrated the invention embodiedin a preferred form" of control apparatus,fiit will be understood thatthe apparatus shown may be varied considerably Withoutdeparting; fromthe ,true spirit and .W hat Ielaim as" new and desire to secure byLetters Patent of the UnitedStates is:

. 1. The combination with an electricinotor,

of'means for automatically reversing; the operationoi the electricmotorcomprising a device for mechanically retarding the motor to cause themotor current to increase and an electromagnetically controlledreversing switch responsive to such increase in current. a

--2. In combination, an electric motor, a device reciproeated therebybetween prcdeterminedlimits-at whichfurther operation of the device isarrested, causlng the motor to stall and'tl1e-;motorcurrent to ncrease,and

"a reversing control for said motor compris- Iing means automaticallyoperated responsively to the 111016866- ofthe motor current by reason ofthe stalling of the motor for.

effecting automatic reversalfof the motor.

The combination of an electric motor,

means forreversing the direction of rotat-ion of the motor, means forstalling the mo f tor after limited operationthereot in eachil'lI'GCJiOH, and electroresponsive means connected tobe energizedyinvaccordancewith the-stalled current of the notor for controllingoperation of said reversing means to reverse the motor; when themotorstalls. I fiThe combination of an electric motor, meansfor-reversing the directionoi rotation of the motor, means for retardingthe motor after a limited operation thereofiin each The combination of areversible electric motor,"electroresponsive' reversing switch Imechanism for establishing power connect ions to operate the motor ineach direction, means tor retarding-the motor upon a predetermined;operation thereof in at least one direction to cause the power currentof the motor to increase, a relay electrically connected to the motor tobe operated responsively to. the increased power current of the motor,and means including connections controlled by the relay through whichthe energization of said electroresponsive reversing switch mechanism iscontrolled to reverse the 'motor upon the retardationthereof.

6; The combination of an electric motor, switch mechanism forreversing'the power connections of themotor, means for stalling themotor after limited operation thereof in each direction, anelectroresponsived'evice connected to be operated responsively to thestalled current of the motor, and

means under the control ofsaid electrore-' sponsive means for operatingsaid switch mechanism to reverse the motor power connections'when themotor stalls. i

7. he combination of a reversible electric motor, electroresponsivereversing switch mechanism for establishing power connections tooperatethe motor in each direction,

means for stalling the motor upon a predetermined operationthereof ineither direction, a relay electrically connected with the motor to 'beoperated responsively to the stalled current of the motor, and meansincluding connections controlled by the relay through which'theenergization of said electroresponsive reversing switch mechanism iscontrolled to reverse the motor upon the stalling thereof. 7 v I 8. Thecombination of a reversible electric motor arranged tobe stalled afterlimited operation thereof in-each direction,

switch mechanism for controlling the motor power connections toalternately operate the motor in each direction, and electroresponsivemeans electrically connected with the' motor to be energizedinaccordance with the stalled current of they motor and ar meansconnected to be energized in accordand cooperating with said first meanstoicon- GDv ance with the stalled current of the motor trol operationcofsaid separately operable switch toreverse the motor power connec- "tionswhen the motor stalls.

10. The combination of a reversible elec-' tric motor, arranged to bestalled after limitedoperation thereof in each direction of rotation, apair-of separately operable elec troresponsive switches, each forcontrolling power connections to operate the motor in 'a difierentdirection or rotation, a relay for controlling the energization of saidseparately operable switches and arranged to effect operationof eachswitchto establish power connections controlled thereby after operationof the other switch to interrupt the power connections con-trolledthereby, and; anelectroresponsive relay connected in circuit, with themotor to be energized in accordance with the stalled current of themotor in each direction of rotation thereof and, arranged to effectoperation of saidfirst relay when the motor stalls. r

11., 'The, combination of a reversible electric motor arranged to beretarded, after limited operation. thereof in at least one direction ofrotation to cause the motor current to increase above a predeterminedvalue, means for reversing the direction of rotation of the motor,electroresponsive'means connected to be'operated responsively to'saidpredetermined value of the motor current and arranged to efi'ectoperation of said means to reverse the motor, and means for renderingsaid electroresponsive means ineffective during the startingv of themotor in saidone direction of rotation.

12. The combination of a reversible electric motor, means for retardingthemotor afterlimited operation thereof in each direction of rotation'tocausethe, motor current to increase above va predetermined value, meansfor reversing the dlrection of rotation "of the motor, electroresponsivemeans connected to beloperated responsively to said predetermined valueof the motor current and: arranged to eflect operation of said means toreverse the motor, and means co- "operating with said electroresponsivemeans- Vresponsive device connected in circuit with the motor arrangedto be operated responsively to apredetermined :value of current in themotor circuit, connectionscontrolled by said device through which theenergization of said electroresponsive switch mechanism is controlled toreverse the motor when the motor is stalled, and time element meansassociated with said reversing switch mechanism and cooperating withsaid deviceto prevent reversal ofthe motor when the starting currentthereof exceeds said prede termine d value. a

In witness whereof, I have hereunto set my hand this 14th day ofJulv'1926.

LOUIS J. WEBER;

